Speaking at PortMiami, Sessions suggested one reason Chicago has the country’s highest number of homicides is that it’s a so-called sanctuary city – it refuses to help the Trump Administration detain undocumented immigrants. Since Miami-Dade County helps the feds nab immigrants, he inferred, it has less violent crime.

Never mind that there’s no evidence linking sanctuary cities to increased violent crime – or that the authors of the one study Sessions cites as evidence insist he misrepresented their data.

In politics, Sessions can get away with his specious logic because it’s based on a convenient impression: Chicago thumbs its nose at federal immigration enforcement; therefore undocumented criminals must be running amok; that in turn must contribute to the Second City’s runaway murder tally.

It’s the sort of bogus syllogism Sessions’ boss, President Donald Trump, keeps etched on his own Teleprompter. It’s been fueling Trump's triumphant demonization of immigrants ever since he launched his campaign two years ago calling Mexican migrants rapists and drug traffickers.

Research shows undocumented immigrants commit fewer crimes on average than native-born Americans. So how do President Trump and his surrogates get away with their nonsense that Mexicans are hell bent on ramping up violent crime in the U.S.?

In part it’s because, like Chicago, Mexico seems so hell bent on raising violent crime on its own turf.

Trump can sell his snake-oil assertion that bad hombres are pouring out of Mexico into the U.S. because that's the impression so many bad hombres inside Mexico have gifted his nativist road show.

Why could Trump lead a rally in Arizona Tuesday night and hear the desert roar in xenophobic approval when he threatened to shut down the government if he doesn’t get funding for his nutty border wall? He was no doubt emboldened just hours earlier when the State Department warned Americans against traveling to various regions of Mexico – even popular tourist destinations like Cancún – because of rampant narco-mayhem and murder.

Mexico, in fact, is home to two of the world’s five most murderous cities, according to rankings from the Mexico-based Citizens’ Council for Public Security. In other words, Trump can sell his snake-oil assertion that “bad hombres” are pouring out of Mexico into the U.S. because that’s the impression so many bad hombres inside Mexico have gifted his nativist road show.

No matter that one reason Mexican migrants come here is to escape Mexico’s violent crime. Ditto for migrants from other parts of Latin America and the Caribbean. But the president can finger them as criminal threats – and score major points with his America First base in the process – because the murder rates in many of their countries make Chicago look calm.

MOST DANGEROUS CITIES

According to the Citizens’ Council, 23 of the world’s 25 most dangerous cities are found in Latin America and the Caribbean. That’s not a typo.

The worst: Caracas, Venezuela, with a horrific 130 homicides per 100,000 residents. The U.S. has only five per 100,000. That’s an epic disparity that Latin American leaders need to ponder a little more seriously the next time Trump tweets another immigration-related warning about the bad hombres in their countries.

Relatives of a priest murdered by gangsters in Mexico's Veracruz state mourn at his funeral last year.

Credit Marco Ugarte / AP via Miami Herald

Because the problem is, they don’t take it seriously enough. Nightmarish violent crime, especially drug-related homicide, has been plaguing Latin America for decades now; but most Latin American governments have done precious little to upgrade their meager police and judicial institutions, not to mention meaningful economic opportunity.

Just before Mexican President Enrique Peña Nieto took office in 2012, I pressed him in an interview about his plans for reining in Mexico’s narco-violence. His answer was vague at best. In fact, his aides wanted me and the rest of the international media to stop making such a big deal about it. Our articles were a drag on foreign investment.

No, Señor Presidente – drug-cartel corpses on the streets of Cancún are a drag on investment. And you know what else would be a drag on your economy? A drastic reduction in the record level ($25 billion last year) of remittances your country’s receiving from Mexican migrants in the U.S. Which may hit you if President Trump gets his way on immigration.

And he and his administration’s other master logicians can get their way thanks in no small part to bad politicos like you – who let bad hombres have the run of your countries.

Update: Three days after this article was published, President Trumped sent out this tweet:

U.S. Attorney General Jeff Sessions came to Miami-Dade County on Wednesday to thank it for helping the feds deport undocumented immigrants. But experts say his claims about crime in cities that don’t cooperate – so-called “sanctuary cities” – are exaggerated.

This year President Trump ordered local governments to comply with federal requests to detain undocumented immigrants who’ve been arrested. He warned sanctuary cities they would lose federal law enforcement funding if they didn't.